Hydraulics opinion

Hoping to not open a can of worms but what is the opinion on suction strainers on mobile machines. My skid steer came with a suction strainer for the charge pump and a separate suction strainer for the gear pump. Never had a problem in this regard but a lot of equipment has done away with suction strainers because they don't do much and can lead to cavitation. Curious what others think?

I dont use them...when it is cold outside there is no bypass

The suction strainer is your last line of defense for your pumps. I can't imagine a good reason to take them out. Rondig had mentioned Cold weather start up. If that's the case why not just run a lower viscosity oil?
You're right about a year ago there was a serious debate about whether or not the use of a suction strainer was prudent. My position is if the manufacturer decided it was useful then it should be there because they are not in the habit of spending money on something that they don't have to do

Good luck

I think you will be looking hard to find a mass produced machine that doesnt have some kind of screen/filter before the charge pump, or right after it.... There won't a loop direct to tank..... Not so long as oil buckets with dirt in the bottom

Screen before the pump - to stop the pump crapping itself as a result of whatever might be sucked from the tank.
Screen after the pump - to stop shrapnel from a pump failure contaminating the whole system.
First one needs servicing every time the hydraulic oil is changed, second one only needs servicing in case of a mechanical hernia in the pump.

Agree 100% with fwf & mb that if there are suction/cavitation issues in cold weather with a suction screen in the system then the oil is too high a viscosity.

Thanks for the replies. A couple of sites online make it out that suction filters will destroy your hydraulics.

Welder Dave said:

Thanks for the replies. A couple of sites online make it out that suction filters will destroy your hydraulics.

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They meant NOT having one will destroy your system. Probably a simple auto-correction!?

Welder Dave said:

Thanks for the replies. A couple of sites online make it out that suction filters will destroy your hydraulics.

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Are you kidding? If you have seen the junk I have seen stuck to suction screens... you would never ask that question.

Here's a couple. Some people on this forum take the 1st guy as being the gospel on hydraulics.

http://www.insanehydraulics.com/letstalk/suction.html

https://www.hydraulicspneumatics.com/blog/truth-about-hydraulic-suction-strainers

I respectfully disagree with the positions stated. I stand by my earlier position. A manufacturer is not, NOT, no way in hell, going to spend one nickel on anything deemed unnecessary. Excavators have sump strainers. Loaders usually have return filter well with standpipes in the tank to not draw the trash off the bottom. Pavers, rollers, grinders screened inlet manifolds inside the hydraulic tank. That's a lot of unneeded expenditure that those shareholders are gonna want back, ya think?
I'm typing here, albeit slowly, I can see how it mind sound snippy, it's not meant that way.
If your equipment pump $h!ts the bed, after it hurts your function, what stops it from hurting your travel pump? If your travel motor craps out and spews trash out case drain port, what protects the rest of your system, the strainer. Everyone thinks that filters are 100% efficient. If you look at your schematics, usually only half or 3/4ths of the oil pumped is filtered on the way back. Some sneaks back in case drain, which may or may not be filtered, some gets by filter in bypass mode. Murphy is everywhere, waiting for us to slip up. You don't have to invite him over for breakfast.

This image is a sump strainer I serviced Wednesday. That sludge is all kinds of evil. Bits of steel, piston packing, bits of back up ring, slivers. All things bad for an excavator. The screen was there to stop it. That could have been laying waste to the entire system.

Hey!! Wait!! The internet don’t lie.

Vetech63 said:

Hey!! Wait!! The internet don’t lie.

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You're right, the internet doesn't lie, it's the muhfuggers who post on it, spreading disinformation and shenanigans.

And for a bit of lightening up

Thanks for that. I think the OEM's would specify suction strainers with much higher flow rates than what the machine actually has so there is no chance of cavitation. One of the arguments I read is that suction strainers were installed because that was standard practice back in the day and they don't want to break tradition. Here's another one saying not to use them.

https://www.mobilehydraulictips.com/7-ways-avoid-cavitation/

I read those articles with a growing feeling of incredulity, as in "You what..?" or more like "You fcuking what..?"

I think that there has to be a differentiation made between machine hydraulic systems and industrial hydraulic systems in regard to the environment in which they operate.

Also one statement made me (kinda) laugh, quote "Don’t get me wrong, it could take an easy decade to clog a suction filter, but when it does clog, ........" My response - well service the f**king thing as per the manufacturer's recomendations then, which is every time the oil is changed, usually one year or 2000 hours intervals. That way your suction strainer will never reach the decade it needs to clog. FFS can I have some of whatever these clowns are smoking..?

Still have the OE Strainers on my Antique Allis, know why they are there and could have cut them out but ARE cleanable and a NECESSITY especially on OLD ABUSED machines. One Dope/Dumbazz gets his hands on a machine and red glues ALL the gaskets back in place instead of buying new or fabri-cobbling replacements or just using it to compensate for lack of skill and you WILL understand the necessity of strainers.

DMiller said:

Still have the OE Strainers on my Antique Allis, know why they are there and could have cut them out but ARE cleanable and a NECESSITY especially on OLD ABUSED machines. One Dope/Dumbazz gets his hands on a machine and red glues ALL the gaskets back in place instead of buying new or fabri-cobbling replacements or just using it to compensate for lack of skill and you WILL understand the necessity of strainers.

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Worked on many an Allison 5-6,000 series with convertor housing scavenge screens plugged solid with silicone drippings from people that don't believe in new gaskets.

Welder Dave said:

Thanks for that. I think the OEM's would specify suction strainers with much higher flow rates than what the machine actually has so there is no chance of cavitation. One of the arguments I read is that suction strainers were installed because that was standard practice back in the day and they don't want to break tradition. Here's another one saying not to use them.

https://www.mobilehydraulictips.com/7-ways-avoid-cavitation/

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Most mobile equipment has a pressurized system just for cavitation control. I've set many a Wabco scraper up to be pressurized by the air brake system with a regulator and check valve to boost the steering system. It made a huge difference in steering response and lack of cavitation pitting in the valve block on the pump. Waiting for the system to pressurize from heat took far too long.
And all those machines had the suction screens serviced on a regular basis.

I try to use 518 wherever I can in place of silicone. It doesn't glob up to plug orifice and passageways like sillycone does.
I've seen many problems, cooling systems, lube systems, hydraulics, even had a power divider crap the bed from too much sealant.